Determine a,b and c so that curve y= ax^3 + bx^2 + cx will have a slope of 4 at its point of inflection (-1,-5)

Question

Help please!

Answer 1

-5 = -a + b - c

y' = 3a x^2 + 2b x + c
... 4 = 3a - 2b + c

y" = 6a x + 2b
... 0 = -6a + 2b

3 equations, 3 unknowns
... solve the system

Answer 2

You might have check my solution given earlier before reposting the problem:

http://www.jiskha.com/display.cgi?id=1486538658